Reduce Blizzard Cooldown

Can someone please explain why Blizzard has a 3.5 second cooldown? Its skill effect is inferior to Fissure’s and Elemental Storm’s (both Tier 2) and yet its cooldown is over twice as long. Why not make it have a cooldown in the 1 to 2 second range, in line with other Tier 2 offensive devotion skills?